Medicinal plants are the local heritage with global importance, World is endowed with a rich wealth of medicinal plants. Herbs have always been the principal form of medicine in India and presently they are becoming popular throughout the developed world, as people strive to stay healthy in the face of chronic stress and pollution, and to treat illness with medicines that work in concert with the body's own defense. People in Europe, North America and Australia are consulting trained herbal professionals and are using the plant medicines. Medicinal plants also play an important role in the lives of rural people, particularly in remote parts of developing countries with few health facilities.

The variety and sheer number of plants with therapeutic properties is quite astonishing. It is estimated that around 70,000 plant species, from lichens to towering trees, have been used at one time or another for medicinal purposes. The herbs provide the starting material for the isolation or synthesis of conventional drugs.

In Ayurveda about 2,000 plant species are considered to have medicinal value, while the Chinese Pharmacopoeia lists over 5,700 traditional medicines, most of which are of plant origin. About 500 herbs are still employed within conventional medicine, although whole plants are rarely used.In India, medicinal plants have made a good contribution to the development of ancient Indian Material Medica. One of the earliest treatises on Indian medicine, the Charak Samhita (1000 B.C.), records the use of over 340 drugs of vegetable origin. Most of these continue to be gathered from wild plants to meet the demand of the medical profession. Thus, despite the rich heritage of knowledge on the use of plant drugs, little attention had been paid to grow them as field crops in the country till the latter part of the nineteenth century.Medicinal plants help in alleviating human suffering. These plants "are being integrated to the field of foods as additives, beverages and cosmetics. They are widely used as sweeteners, as biters, as spices, as natural colouring agent and as insecticides. Mass selection recurrent selection, hybridization, clonal selection mutation and biotechnology are some of major techniques at their use for many proven medicinal plants. There are still several constraints.During the past one century there has been a rapid extension of the allopathic system of medical treatment in India. It generated commercial demand for pharmacopoeial drugs and their products in India. Efforts have been made to introduce many of these drug plants to farmers. Several research institutes have undertaken studies on the cultivation practices of medicinal plants, which were found suitable and remunerative for commercial cultivation. The agronomic practices for growing poppy, isabgol, senna, cinchona, ipecac, belladonna, ergot and few others have been developed and there is now localized cultivation of these medicinal plants commercially.

Medicinal plants have curative properties due to the presence of various complex chemical substances of different composition, which are found as secondary plant metabolites in one or more parts of these plants. These plant metabolites, according to their composition, are grouped as alkaloids, glycosides, corticosteroids, essential oils, etc. The alkaloids form the largest group, which includes morphine and codeine (Poppy), strychnine and brucine (Nux vomica), quinine (Cinchona), ergotamine (Ergot), hyocyamine (Belladonna) scolapomine (Datura), emetine (Ipecac), cocaine (Coco), ephedrine (Ephedra), reserpine (Rauwolfia), caffeine (Tea dust), aconitine (Aconite), vascine (Vasaca) santonin (Artemisia), lobelin (Lobelia) and a large number of others. Glycosides form another important group represented by digoxin (Foxglove), stropanthin (Strophanthus), glycyrrhizin (Liquorice), barbolin (Aloe), sannocides (Senna), etc. Corticosteroids have come into sannocides (Senna), etc. Corticosteroids have come into prominence recently and diosgenin (Dioscorea), solasodin (Solanum sp.), etc. now command a large world demand. Some essential oils such as those of valerian kutch and peppermint also possess medicating properties and are used in the pharmaceutical industry. However, it should be stated in all fairness that our knowledge of the genetic and physiological make-up of most of the medicinal plants is poor and we know still less about the biosynthetic pathways leading to the formation of active constituents for which these crops are valued.Medicinal and aromatic plants are found in forest areas throughout South Asia, from the plains to the high Himalayas, with the greatest concentration in the tropical and subtropical belts and arid region of Thar desert. India recognizes more than 2,500 plant species as having medicinal value, Sri Lanka about 1,400, and Nepal around 700. Some of these, found at high altitudes in particularly stressful environments, grow very slowly and cannot live elsewhere. Others are more broadly distributed and adapt more easily to different ecological conditions.

During the past decade, a dramatic increase in exports of medicinal plants attests to worldwide interest in these products as well as in traditional health systems. In the last 10 years, for example, India's exports of medicinal plants have trebled. But with most of these plants being taken from the wild, hundreds of species are now threatened with extinction because of over-harvesting, destructive collection techniques, and conversion of habitats to crop-based agriculture. For instance, the small coniferous Himalayan yew (Taxus baccata) has recently become a heavily traded species. Similarly, senna is being grown extensively in arid region of India.The pharmaceutical industries have made massive investment on pharmacological, clinical and chemical researches all over the world in past five decades. Efforts have been made to discover still more potent plant drugs. In fact, a few new drug plants have successfully been passed the tests of commercial screening. The benefits of these efforts would reach to the masses in future if farmers initiate commercial cultivation of medicinal plants. In fact, agricultural studies on medicinal plants, by its very nature, demand an equally large investment and higher priority. India, in particular, has a big scope for the development of pharmaceutical and phytochemical industry.The subcontinent, India is blessed with varieties of aromatic and medicinal plants. The agroclimatic conditions and rainfall favouring this bio-availability. More than 7,500 species of medicinal plants are grown in India. Owing to this India is considered as the botanical garden of the world and treasure house of the biodiversity. Ayurveda, our indigenous system of health care is accepted everywhere especially abroad. Vedas and other ancient scriptures give cleanout evidences of using herbs and medicinal plants. Ayurveda alone describes about 2000 species of plants, which constitutes more than 10,000 formulations.Over the past 10 years there has been a considerable interest in the use of herbal medicines in the world. Regarding the export of medicinal plants India's contribution to the international market is comparatively very low. Utilizing our biodiversity and proper planning, Indian products can very well enter the overseas markets. This can be achieved only through proper development of medicinal plants, standardization of the extracts and keeping the quality. WHO has recognized the effectiveness of traditional system of medicine and its safety.The Indian Pharmacopoeia (1966) recognized eighty five drug plants whose ingredients are used in various pharmaceutical preparations. The text is however; confine to a few important commercially grown medicinal plants whose cultivation deserves priority in out national economy.According to R. B. S. Rawat and R. C. Uniyal, National Medicinal Plants Board Department of ISM&H (Agrobios News Letter, Vol. 1, No. 8, January 2003) the use of medicinal plants is as old as human civilization. India has a glorious tradition of health care system based on plants, which dates back to Vedic era. In Rig Veda which is the oldest known repository of human knowledge and wisdom (4500-2500 B.C.) mentions about hundred medicinal plants used by the Aryans while in Atharva Veda (2500-2000 B.C.) elaborate description of medicinal plants are given. Later in Samhita period the science of medicine systematically organized with clear concept and theories based on the treatises the Charak Samhita - 2000 B. C, Sushruta Samhita - 1000-800 B.C. Besides this there are other works on Ayurveda and medicinal plants by Nagarjun, Chakradatta, Sharangadhar and Bangasen - 1000-500 B.C. Vaghabhatta Junior - 800 A. D. complied most of the books on Ayurveda and wrote Ashtanga Hariday Samhita.They further indicated that India is bestowed with unique diversity in culture and natural vegetation exhibiting rich plant diversity. It has all known types of agro-climatic, ecologic and edaphic conditions. It also have unique biogeographical positions having all known types of eco­systems ranging from coldest place, the dry cold desert of Ladakh (Nubra Valley with - 57°C), to temperate, alpine and sub-tropical regions of north-west and trans-Himalayas; rain forests with high rainfall; wet evergreen humid tropics of western ghats and arid and semi-arid regions of peninsular India; dry desert conditions of Rajasthan and Gujarat to the tidal mangroves of Sunderban. It harbors 17500 flowering plants out of which 2000 plants are used in various classical system of medicine like Ayurveda, Siddha and Unani. The tribal and other communities use about 8000 species of wild plants as traditional medicine. The drugs used in ISM are 90% based on plant material and are considered to be safe, cost effective and with minimal or no side effects when genuine ingredients are used. Medicinal plants are living and irreparable resource, which is exhaustible if over used and sustainable if used with care and wisdom. The importance of medicinal plants has been overlooked in the past. However, at present medicinal plants are looked upon not only as a source of affordable health care but also as a source of income. According to WHO report, over 80% of the world population relies on traditional medicine largely plant based for their primary healthcare needs.

The forest areas have been the traditional source of medicinal plants and herbs. The position cannot be sustained much further because on the one hand the areas under forests have been steadily shrinking and on the other the requirement of medicinal plants and herbs has increased steeply. This has resulted in unscientific and over exploitation of medicinal plants in the forests. One indication of the scarcity of some medicinal plants is their steep prices. The Ministry of Environment and Forests have already banned 29 endangered species of medicinal plans from their natural habitat. While medicinal plants are being utilized in the preparation of a number of modern drugs, there is a new trend worldwide of using natural products. Besides medicinal values, Pharmaceuticals, herbal food supplements, toiletries and cosmetics are growing in consumption in the international market.